Martin Scorsese’s Taxi Driver has been viewed a couple of times in my house in the past few days, and I’ll admit what by now should be painfully obvious: it just keeps getting better. Indeed, Taxi Driver is a film that is both solidly of its time and place (New York City, 1976) but still powerfully relevant today. I don’t think it’ll ever “get old.” It’s one of those movies you can watch a dozen times in your lifetime and interpret differently each time. It remains fascinating on every gritty, grimy level and is probably Scorsese’s best film.

For some, Scorsese has always been an acquired taste. His films are personal, New York-centric, violent, operatic, and hard to like. I once knew a film fanatic who, for whatever reason, never got all that deeply into Scorsese’s work, though he admired it, I guess, on an abstract level. Parts of Scorsese’s resume, in my opinion, are overrated, and he won the Oscar for entirely the wrong film, The Departed, which is more or less unwatchable. But the good parts of his resume are resoundingly great. GoodFellas will remain one of my 10 favorite films, and The King of Comedy, The Wolf of Wall Street, Shutter Island, Raging Bull, Casino, The Aviator, and Taxi Driver, for sure, are equally unforgettable.

The movie might not be so well-regarded without Robert De Niro’s incredible portrayal of Travis Bickle. It’s one of the great screen performances, for a host of reasons other than just “you talking to me?” He burrows deep into the sick, feverish, twisted mind of Bickle, who stares out of his cab every night to see a bleak vision of New York City. The place is a hell, a depraved prison in which pimps, whores, junkies, muggers, robbers, adulterers, lunatics, and other assorted street trash act out their daily dramas without regard for the rest of humanity. Travis is sickened by them, while others in the city – the so-called normal people – seem immune. Bickle, who seemingly has no defenses against the moral rot of New York, descends deeper into madness.

It’s hard to think of another movie that portrays loneliness and isolation with more detail or sympathy. Travis is alone and knows he is alone; detached, wandering, he forgets how to interact with other people. He sees only what he wants to see – the street trash – and indulges this fetish by driving a cab at night. He pulls in decent tips but lives in a classic New York City coldwater flat, which is barely large enough to accommodate one man. He tries striking up friendly conversations with people, but he’s awkward, weird, and hard to like. Also, there seem to be multiple versions of Travis; it’s almost as if he’s trying on different personas to see which one works. There’s gregarious Travis (awkward), standoffish Travis (more awkward) and obnoxious Travis (even more awkward). Nothing sticks; he has no social skills whatsoever. His inability to connect with others makes life a prison of its own.

De Niro suggests Travis’ desperation by making him quiet and still; when Travis breaks out into a grin, you know there’s a screw loose somewhere, but De Niro keeps everything internalized, so that we can’t quite comprehend the nature of the problem. Travis himself is barely able to articulate his complaint. In an affecting scene, he tries talking it out with Wizard (Peter Boyle), but can only communicate a few meaningless syllables. “I feel like … I don’t know, I feel like doing something,” he mumbles, clearly aware that he’s capable of something terrible, but unable to explain it.

Two women stand out in Travis’ waking nightmare: Betsy, a political operative played by Cybill Shepherd, and Iris, a 12-year-old prostitute played by Jodie Foster. Both are blonde and blue-eyed; both, in Travis’ twisted view, require saving from exploitative systems. Unfortunately, Travis fails to communicate effectively with either woman. He takes Betsy on an abortive date to a porno, and annoys Iris with his moralizing lectures. Unable to get through to Betsy, he plots to assassinate her boss, a powerful politician, and in order to save Iris, he gears up to murder her pimp, Sport (played by Harvey Keitel). His personal failures trigger him to go on a mission to fulfill his darkest fantasies.

Travis spirals through a hell of missed opportunities, garbled communications, and walking hallucinations. He desperately needs sleep – or some time in a mental ward – but like so many other crazies, he’s loose on the street, engaged in destructive fantasies with little or no bearing on the real world. His craziness seeps out of his pores; he is unable to hide it. Betsy knows there’s something “off” with Travis, but dates him, anyway, perhaps out of sadistic curiosity. Travis’ fellow cabbies know he’s sliding over the edge, but are powerless (or unwilling) to help. Only the Secret Service agent who Travis unwisely engages in conversation realizes he is unstable, but by then, the situation cannot be reversed.

Travis reaches a turning point (even admitting as much on the soundtrack) when he purchases a bunch of handguns off an amoral street dealer dressed like a banker. This is my favorite moment in the movie, as the dealer lays out his wares and describes each pistol in loving detail. Travis fondles the guns, sighting down their barrels, zeroing in on people on the street. He asks good questions and gets solid, reliable answers. Clearly, he’s going to kill people with these guns, but the dealer doesn’t care.

Another favorite moment comes when Travis confronts Sport for the first time. Sport sees something dangerous in Travis but can’t put his finger on it, marking him, incorrectly, as an undercover cop. This offends Travis – you can see it in De Niro’s eyes. “Hey, I’m no cop,” he insists, but Sport, who is nothing if not street smart, still smells a rat. Later, when Travis comes back with guns and a Mohawk, Sport finds out exactly who he is.

The final shootout in which Travis kills a number of ostensibly bad guys in the name of “saving” Iris is straight out of a horror movie – gory, frightening, realistic. Why does Travis do it? Because that was the road he was going down the entire time. His whole life has built to this moment. He tells us early on that “a real rain” is going to wash away the scum, and the men he kills fit that description.

The closing moments are puzzling, and it is possible that we shouldn’t take them literally. I think they are Travis’ dying fantasy, and Scorsese suggests as much by showing Travis’ eyes in the rearview mirror, glancing at something, fleetingly, that isn’t there. The movie is a night terror, an insomniac’s hallucination.